Effect of deformation behavior on the evolution of microstructure of RAFM steel subject to closed-dual equal channel angular pressing

• Published in: Fusion engineering and design Vol. 184; p. 113307
• Main Authors: Xue, Kemin, Wang, Zhaoyu, Tian, Wenchun, Dai, Jiren, Hu, Qinghang, Li, Ping
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.11.2022; Elsevier Science Ltd
• Subjects: Closed-dual equal channel angular pressing; Deformation effects; Elongation; Equal channel angular pressing; Evolution; Ferritic stainless steels; Grain size; Martensitic stainless steels; Microstructure; Precipitation size; RAFM steel; Shear deformation; Grain size; Precipitation size; Closed-dual equal channel angular pressing; RAFM steel
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2022.113307

•The large size ultrafine crystalline material was obtained successfully by C-DECAP process.•The effect of interaction of adjacent deformation zones on the microstructure evolution is revealed.•The mechanism of the change in size and volume fraction of the precipitation is clarified. In this paper, the microstructure evolution of RAFM steels during multi-pass closed dual-equal channel angular pressing was studied. The results show that multi-pass closed dual-equal channel angular pressing deformation can significantly refine the grain and precipitation size. The average grain size of martensitic lath is refined from ∼3.16 μm to ∼0.71 μm, after four passes. The average size of M23C6 precipitation in elongation and shear deformation zone decreases from 132.14 nm to 109.97 nm and 107.79 nm, respectively. The average size of MX precipitation in elongation and shear deformation zone decreases from 51.8 nm to 35.54 nm and 28.56 nm. The initial volume fraction of M23C6 and MX precipitation is 3.48% and 0.59%, respectively. With the increase of deformation passes, the volume fraction of both precipitations shows a trend of increasing first and then decreasing. The volume fraction of M23C6 precipitation in elongation and shear deformation zone reached the peak value of 4.18% and 4.10% after the second and third pass and was 3.21% and 2.91% after four passes of deformation, respectively. The volume fraction of MX precipitation in elongation and shear deformation zone reached the maximum of 1.84% and 1.71% at the third pass, respectively. After four passes of deformation, the volume fraction of both regions are 1.72%, and 1.67%, respectively.